To unlock this, you only have to complete the Pore Stuffing Task 50 times in the War Against the Hive Quest.

Orockle will give you a Gooey Substance. Travel to the east side of the Hive area and use the Gooey Substance on 7 Hive Pores. They summon three Lesser Swarmers from time to time so beware of being trapped.

After using Gooey Substance, Lesser Swarmers vanish and the pore changes to Overgrown Hive Pore for 60 seconds before returning. After disabling 7 Hive Pores you will receive a message indicating you are done with the mission. You can disable the same pore 7 times, but it will be quicker to do different pores.

Return to Orockle when you are done and you will receive your rewards. By repeating this mission 50 times you will get the achievement Pimple